Ignition timing control means for internal combustion engines



Nov. 10, 1942. M. MALLORY 2,301,553

IGNITION TIMING CONTROL MEANS FOR INTERNAL COMBUSTION ENGINES Filed Dec.11, 1941 m 3 'T l N LO Q m N I 1 H} INVENTOR. MARION MALLORY PatentedNov. 10, 1942 IGNITION TIMING CONTROL MEANS FOR INTERNAL COMBUSTION ENGINE-S Marlon Mallory, Detroit, Mich. Application December 11, 1941,Serial No. 422,488

7 Claims.

This invention relates to ignition timing control means for internalcombustion engines.

The principal obje t of my invention is to control the pressures in theintake passageway of an internal combustion engine so that a singlesuction operated device will retard the spark timing when the engine isidling, advance the spark timing when the engine is working under lightloads, and reduce the advance of the spark timing when the engine isworking under full loads. This eliminates the commonly known centrifugalgovernor used in present day ignition systems.

Fig. 1 is a sectional view partly in elevation showing the mechanism ofmy ignition timing control means for an internal combustion engine.

Fig. 2 is a section along the line 2-2 of Fig. 1.

The carburetor 1, adapted for attachment to an internal combustionengine, is provided with an intake passageway 9 having an air inlet enddesignated 9 and a fuel mixture outlet l9 through which the fuel mixtureis adapted to pass into the engine intake manifold.

The passageway 9 includes the venturi H and I for purposes ofdescription rather than by way of limitation, a booster venturi I2 ispositioned within the main venturi ll. usual butterfly throttle valvemounted within the passageway 8 on shaft 3 which is swung open andclosed by the rod H and crank l5. float bowl is designated I6.

The fuel Fuel is drawn from I3 designates .the

the float bowl through passageway ll into the mixing chamber.

A conventional timing mechanism is shown consisting of the usualrotatable cam l8 which operates the electrical circuit breaker i9mounted on plate 29 which can be rotated clockwise to advance the sparkand counterclockwise to retard the spark. A suction device 2| is usedfor advancin'g and retarding the spark. The suction device comprises aflexible diaphragm 22 backed up by a compression coil spring 23. Thediaphragm is mounted in housing 24 which is connected to the carburetorby conduit 25. The diaphragm is connected to plate 29 by rod 26, one endof which is'pivotally connected as at 21 to the plate 20 and the otherend of which is fixed to the diaphragm. The wall 29 of the housing isperforated so that the diaphragm is subjected on the outside toatmospheric pressure whereas on the inside of housing 25 the diaphragmis sub- .lected through line 25 and passageway 29 and orifice 5 andpassageway 2 to certain pressure conditions obtaining in and created bythe intake passageway 8, as described below.

Passageway 29 communicates with conduit 25 and through orifice 6communicates with venturi l2. If desired, passageway 29 can be connectedinto the large venturi I I preferably at the point of greatestrestriction, that is, adjacent the lower end of small venturi l2.Passageway 29 communicates with passageway 2. Passageways 29 and 2 areboth formed in the wall of the carburetor. The wall of the carburetor isalso provided with a passageway 5, the inner end of which communicateswith the mixture outlet III and the other end of which, at certainpositions of the throttle valve I 3, communicates with the passageway 9in the throttle, valve shaft 3, as explained below. The carburetor isalso provided with a choke valve 30 mounted on shaft 3! and controlledby the usual choke rod 32.

The operation of When the engine is idling the throttle valve II will bealmost closed or in idling position and conduit 2 is closed by thethrottle shaft 3. At this time the suction device 2| communicates withintake passageway 3 only through orifice 6, passageway 29 and conduit 25and the spark is retarded. as shown in the drawing, because the suctiondevice will not be subjected'to enough vacuum to advance the ignitiontimer against spring 23.

As the throttle valve I3 moves toward an open position diametricalpassageway 4 in shaft 3 registers with passageway 5 and with passageway2, thereby-subjecting passageway 2 to the manifold vacuum becausepassageway 5 communicates with the mixture outlet l0 below throttle i3.As soon as passageway 2 is subjected to the intake manifold vacuum this,through conduit 25, sub- Jects the diaphragm 22 to manifold vacuum andthe spark is advanced. If the throttle valve I3 is opened wide or nearits open position, passageway 4 rotates beyond passageways 5 and 2 andpassageway 2 is again shut off by the throttle shaft 3. Thus, in thissystem the high suction in the manifold on the engine side of thethrottle I3, when operating on part throttle or part load, is reduced orbled down by the passageway 29 terminating in the venturi l 2 at orifice6. Bleeding down the manifold vacuum closer to the vacuum created by airflowing through the venturi makes possible the. use of a single suctiondevice. For example, supposing the manifold vacuum was not bled down,there would be approximately 14" or 15" of mercury existing in thesuction device when the engine'was running at normal speeds with thethrottle partly open, and unless a very stiff spring was used in thetimer or suction device, the spark would be advanced too far, and, if astifl spring were used in the timer or suction device to prevent thespark from advancing too far, the stiff spring would not permit thesuction device to advance the spark when the engine was operating onwide open throttle because the maxim'umsuction in the venturi of theordinary carburetor is never higher than 6" or 7" of mercury even atextreme high speeds. Of course, it will be understood that the manifoldvacuum is not bled down to a point as the system is as followsz low asthe vacuum created by the suction in the venturi because more sparkadvance is required when the throttle is only partly open than when thethrottle is full open. The system actually produces two spark curves-onefor part load and one for full load.

I claim: v

1. In an internal combustion engine having an intake manifold, acarburetor-including an intake passageway and a throttle valve therefor,a conduit having one end terminating in the intake passageway of thecarburetor continuously on the atmospheresideof the throttle valve, asecond conduit communicating with the first mentioned conduit, and valvemeans controlling the second conduit whereby the second conduit isplaced in communication with the intake passageway on the engine side ofthe throttle valve at part open throttle and shut off from the intakepassageway at idle position of the throttle, and a uction controlledignition timing device continuously connected to the first mentionedconduit for advancing and retarding the timing of the engine ignitionsystem as the throttle or charge is varied.

2. The combination as claimed in claim 1 wherein the valve meanscomprises a shaft for the throttle valve having a passagewaytherethrough which places the second conduit in communication with theintake passageway on the engine side of the throttle valve at part openthrottle positions and which is disconnected from the second conduit atidling position of the throttle whereby the throttle valve shaft closesoff the second conduit from communication with the intake passageway andthe said suction device responds solely to the vacuum created by theflow of air through the said intake passageway past the end of the firstmentioned conduit.

3. In an internal combustion engine having an intake manifold, acarburetor including an intake passageway and a throttle valve therefor,a venturi in said intake passageway, a conduit having one endterminating in the venturi continuously on the atmosphere side of thethrottle valve, a second conduit communicating with the first mentionedconduit and with the intake passageway on the engine side of thethrottle "valve, a valve in. said second conduit and a connectionbetween said valve and the throttle valve for operating the throttlevalve and the said valve coincidentally whereby the second conduit isplaced in communication with the intake passageway on the engine side ofthe throttle valve. at part open throttle and shut ofi from the intakepassageway at idle position of the throttle, and a suction controlledignition timing device continuously connected to the first mentionedconduit for advancing and retarding the timing of the engine ignitionsystem as the throttle or charge is varied.

4. In an internal combustion engine having an intake manifold, acarburetor having an intake passageway, a throttle valve for said intakepassageway, a venturi in said intake passageway on the atmosphere sideof the throttle valve; a conduit having one end terminating in theventuri of the carburetor continuously on the atmosphere side of thethrottle valve, a second conduit communicating with the first mentionedconduit, and valve means controlling the second conduit whereby thesecond conduit is placed in communication with the intake passageway 'onthe engine side of the throttle valve at part open throttle and shut offfrom the intake passageway at idle position of the throttle, and asuction controlled ignition timing device continuously connected to thefirst mentioned conduit foradvancing and retarding the timing of theengine ignition system as the throttle or charge is varied.

5. In an internal combustion engine having an municating at one end withthe first mentioned I conduit and at the other end with the intakepassageway on the engine side of the throttle valve, a shaft for saidthrottle valve, a valve carried by said shaft interposed in said secondconduit for opening and closing the second conduit coincidentally withthe operation of the throttle valve whereby the second conduit is placedin communication with the intake passageway on the engine side of thethrottle valve at part open throttle and shut off from the intakepassageway at idle position of the throttle, and a suction controlledignition timing device continuously connected to the first mentionedconduit for advancing and retarding the timing of the engine ignitionsystem as the throttle or charge is varied.

6. In an internal combustion engine having an intake manifold, acarburetor including an intake passageway and a throttle valve therefor,a conduit having one end terminating in the intake passageway of thecarburetor continuously on the atmosphere side of the throttle valve, asecond conduit communicating with the intake manifold and with the firstmentioned conduit, and valve mean controlling the second conduit wherebythe second conduit is placed in communication with the intake manifoldwhen the throttle is partly open and out of communication with themanifold when the throttle is at idle position 'or near wide openposition, and a suction controlled ignition timing device continuouslyconnected to the first mentioned conduit for advancing and retarding thetiming of the engine ignition system as the throttle or charge I isvaried.

'7. The combination as claimed. in claim 6 wherein the valve meanscomprises a shaft for the throttle valve having a passagewaytherethrough which places the second conduit in communication with theintake manifold at part open throttle positions and closes offcommunication between the second named conduit and the intake manifoldwhen the throttle is at idling position or near wide open position,whereby said suction device at part throttle positions responds solelyto the manifold vacuum air-bled by the end of the first mentionedconduit terminating in the intake passageway on the atmosphere ide ofthe throttle valve and responds solely to the vacuum created by the flowof air through the intake passageway past the end of the first mentionedconduit at wide open throttle positions,

MARION MALLORY.

